Inverter for supplying load-adaptive boost voltage

Abstract

An inverter which supplies a load-adaptive boost voltage and drives an induction motor includes a reference voltage determining unit configured to determine a reference voltage according to a reference frequency on the basis of a predetermined a relationship between a voltage and a frequency, an inverter unit configured to drive the induction motor according to the reference voltage, and an automatic torque boost voltage calculation unit configured to determine an automatic torque boost voltage value according to a magnitude of an output current from the inverter to the induction motor, wherein the reference voltage determining unit adds a preset manual boost voltage value and an automatic torque boost voltage value to the reference voltage and outputs the resultant voltage value as a final reference voltage.

What is claimed is: 
     
       1. An inverter which supplies a load-adaptive boost voltage and drives an induction motor, the inverter comprising:
 a reference voltage determining unit configured to determine a reference voltage according to a reference frequency on the basis of a predetermined a relationship between a voltage and a frequency; 
 an inverter unit configured to drive the induction motor according to the reference voltage; and 
 an automatic torque boost voltage calculation unit configured to determine an automatic torque boost voltage value according to a magnitude of an output current from the inverter to the induction motor, wherein the reference voltage determining unit adds a preset manual boost voltage value and an automatic torque boost voltage value to the reference voltage and outputs the resultant voltage value as a final reference voltage. 
 
     
     
       2. The inverter of  claim 1 , further comprising:
 a stationary reference frame conversion unit configured to convert an output voltage from the reference voltage determining unit into a voltage of a stationary reference frame and provide the converted voltage of stationary reference frame to the inverter unit. 
 
     
     
       3. The inverter of  claim 1 , further comprising:
 a current detection unit configured to detect a magnitude of a current output from the inverter to the induction motor. 
 
     
     
       4. The inverter of  claim 1 , wherein the automatic torque boost voltage value (Vboost_auto) is calculated by Equation 1 below.
     V boost_auto= Vp _rated× G boost×| io|/|i rated_motor|  [Equation 1]
 
 where Vp_rated is a phase voltage value based on a motor rated sip, Gboost is a boost voltage gain, |io| is a magnitude of an output current, and |irated_motor| is a motor rated output current. 
 
     
     
       5. The inverter of  claim 4 , further comprising:
 a load state detection unit configured to determine whether the induction motor is in a retrogressive mode or a regenerative mode. 
 
     
     
       6. The inverter of  claim 5 , wherein when the induction motor is in the retrogressive mode, the boost voltage gain is set to a retrogressive boost voltage gain (G_boost_motor). 
     
     
       7. The inverter of  claim 5 , wherein when the induction motor is in the regenerative mode, the boost voltage gain is set to a regenerative boost voltage gain (G_boost_gen).